Year	Percent
1990	65.19
1991	63.76
1992	62.29
1993	61.43
1994	60.62
1995	59.83
1996	59.17
1997	59.98
1998	60.08
1999	60.81
2000	61.03
2001	61.22
2002	61.31
2003	61.03
2004	60.55
2005	60.6
2006	61.03
2007	61.31
2008	61.52
2009	60.44
2010	59.84
2011	59.83
2012	59.67
2013	59.06
2014	58.88
2015	58.84
2016	58.48
2017	58.73
2018	59.3
2019	59.28
2020	59.43